A cylinder head may be configured with cam bearing towers to support various engine components such as cam shafts, a fuel pump pedestal and a variable displacement engine mechanism. The cam bearing towers may connect to side walls of the cylinder head to form a rigid support structure having bearing portions that support the cam shaft and fuel pump pedestal. Further, a variable cam timing mechanism may be supported by the cam bearing towers. Alternatively, a cam carrier may be mounted to the cylinder head to support cam shafts and other engine components. The cam carrier may be directly mounted to the cylinder head via a plurality of fasteners to minimize movement and vibration of the assembly.
An example system comprising a plurality of cam carriers mountable to a cylinder head of an engine is shown by Okamoto in EP 1,895,111. Therein, the plurality of cam carriers are mountable to the cylinder head via a plurality of fasteners, each cam carrier having bearing portions to support portions of two cam shafts. The cam shafts are mounted to the cam carriers and secured in place using cam caps and fasteners extended through each cap and the cylinder head.
However, the inventors herein have recognized potential issues with such a system. As one example, the cam carriers are not configured to support a variable displacement engine mechanism for operating deactivatable intake and exhaust valves of particular cylinders in the engine. Further, the cylinder head may not have adequate space for mounting additional engine components, such as a cylinder head cap for mounting a fuel pump.
In one example, the issues described above may be addressed by a system comprising: a cylinder head with a cam bearing tower; a cam carrier insert positioned in the cylinder head; and a camshaft, the camshaft directly supported by the cam bearing tower and directly supported by the cam carrier insert. In this way, the cam carrier insert may include bearing portions that support a variable displacement engine (VDE) mechanism, an intermediate cap and a cam shaft. The VDE mechanism may operate deactivatable intake and exhaust valves of one or more cylinders in the engine.
In other examples, a plurality of cam carrier inserts may be mounted to the cylinder head, each cam carrier supporting a VDE mechanism that operates deactivatable intake and exhaust valves of one or more cylinders mounted in a cylinder block coupled to the cylinder head. Each cam carrier insert may support first portions of a cam shaft coupled to the deactivatable intake and exhaust valves of one or more cylinders. Further, second, different, portions of the cam shaft that couple to non-deactivatable intake and exhaust valves of the cylinders, may be directly mounted to cam bearing towers on the cylinder head. In this way, the system may confer several advantages. For example, the deactivatable intake and exhaust valves in one or more cylinders, may be deactivated by the VDE mechanism coupled to the cam carrier insert while the non-deactivatable intake and exhaust valves of the remaining cylinders remain in operation. In this way, packaging of engine components within the cylinder head may be improved while promoting better engine performance. Further, different engine architectures, such as VDE or an engine without VDE, may be achieved by inserting an appropriate cam carrier insert. For example, without the cam carrier insert, additional machining of the cylinder head may occur.
In further examples, the cam carrier insert may be used with any one cylinder or any combination of cylinders in the engine. In other examples, the cam carrier insert may be used in systems where cam journals are positioned over a cylinder head bolt. In this way, more room may be provided for other engine components such as valve train assemblies coupled to the cylinder head or other engine assembly. In addition, or in alternative examples, the cam carrier insert may be used in combination with a fuel pump or a variable valve lift system. In addition or in an alternative approach, a high pressure fuel pump for supplying fuel to one or more cylinders in the engine, may be coupled to the cam carrier insert. In this way, the cam carrier insert may provide a way of adequately securing the fuel pump to the engine while providing bearing support to other engine components.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.